/*
 * Copyright (c) 2008, 2009, 2011 Oracle, Inc. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
 * which accompanies this distribution.  The Eclipse Public License is available
 * at http://www.eclipse.org/legal/epl-v10.html and the Eclipse Distribution License
 * is available at http://www.eclipse.org/org/documents/edl-v10.php.
 */
package javax.persistence;

/**
 * A class that implements this interface can be used to convert
 * entity attribute state into database column representation
 * and back again.
 * Note that the X and Y types may be the same Java type.
 *
 * @param <X> the type of the entity attribute
 * @param <Y> the type of the database column
 * @since Java Persistence 2.1
 */
public interface AttributeConverter<X, Y> {
    /**
     * Converts the value stored in the entity attribute into the
     * data representation to be stored in the database.
     *
     * @param attribute the entity attribute value to be converted
     * @return the converted data to be stored in the database column
     */
    Y convertToDatabaseColumn(X attribute);

    /**
     * Converts the data stored in the database column into the
     * value to be stored in the entity attribute.
     * Note that it is the responsibility of the converter writer to
     * specify the correct dbData type for the corresponding column
     * for use by the JDBC driver: i.e., persistence providers are
     * not expected to do such type conversion.
     *
     * @param dbData the data from the database column to be converted
     * @return the converted value to be stored in the entity attribute
     */
    X convertToEntityAttribute(Y dbData);
}